1. Field of the Invention
This invention relates generally to the field of automatic telephone call distribution networks and, more particularly, to such call distribution networks in which telephonic calls are sent from one automatic call distributor to another automatic call distributor through a regular public external telephonic network.
2. Description of the Related Art Including Information Disclosed Under 37 C.F.R. Section 1.97-1.99
Automatic call distributors employing a multiport switch controlled by a central processing unit for selectively interconnecting a plurality of interior telephonic units with external telephonic units received at the multiport switch through an external telephonic network are well known. Examples of such call distributors are shown in patent application U.S. Ser. No. 07/770,197 of Jones et al. entitled "Multichannel Telephonic Switching Network With Different Signaling Formats and Connect/PBX Treatment Selectable For Each Channel", filed Oct. 2, 1991, U.S. Pat. No. 5,268,903; U.S. Pat. No. 5,140,611 of Jones et al. entitled "Pulse Modulated Self-Clocking and Self-Synchronizing Data Transmission and Method for a Telephonic Communication Switching System", issued Aug. 18, 1992; U.S. Pat. No. 5,127,004 of Lenihan et al. entitled "Tone and Announcement Message Code Generator for a Telephonic Switching System and Method", issued Jun. 30, 1992 and U.S. Pat. No. 4,627,047 of Pitroda et al. entitled "Integrated Voice and Data Telecommunications Switching System", issued Dec. 2, 1986.
It is also known to send an external telephonic call received at an automatic call distributor to another automatic call distributor in an automatic call distribution network. Examples of such automatic call distribution networks are shown in U.S. patent application Ser. No. 07/960,995 of Blaha entitled "Automatic Call Distributor With Intersubnetwork Customer Information Transfer System and Method" filed Oct. 14, 1992.
In these known systems, a telephonic call made from an external telephonic unit of a regular public telephone network to which the ACD is connected, typically from a customer, is carried through the regular, public external telephonic network to one of the plurality of automatic call distributors (ACDs) in the private automatic call distribution network. Once the call is received, the automatic call distributor logically determines how the call is to be routed. The call is often directed to an agent associated with a gate at the originating ACD to service the call. However, it is desirable in an ACD network having two or more call distributors to route the telephonic call traffic as evenly as possible throughout the network. Therefore, in many situations, a call must be transferred or overflowed to an agent at another ACD in the private automatic call distribution network. The agent receiving the original call may not be able to properly service the customer at the external telephonic unit, thus, the call must be transferred to another agent located at another destination ACD. Moreover, the telephonic traffic flow often exceeds the call capacity of a particular gate at the originating ACD thereby requiring a call to be overflowed to another trunk group or gate at another ACD in the network.
The automatic call distributors in such known systems are placed at various distant locations throughout the network. A call transferred between automatic call distributors is done through dedicated trunks interconnecting the ACDs in the network. Disadvantageously, excessive costs are associated with installing, maintaining and operating these dedicated trunk lines between the ACDs in private automatic call distribution network.
In such known automatic call distribution networks, the transmission of information between automatic call distributor nodes over costly dedicated intertandem trunks or tie lines requires approximately a 1.0 to 1.5 second set-up signalling and verification time between the ACD sending the overflow call and the ACD receiving the overflow call. Thus, there is as much as a two to three second call set up delay when overflowing a call from one ACD to another ACD over dedicated intertandem trunks in known ACD networks. In automatic call distribution networks servicing 1-800 or toll free calls, the user or owner of the network pays for the cost of each call received at a call distributor. Disadvantageously, in such known call distribution networks receiving thousands of calls per hour, a two or three second set-up delay per call costs the user of the network substantial amounts each year.
Furthermore, in such known ACD networks information is sent between ACDs across tie lines as dual tone multiple frequency (DTMF) tones. These tones are transmitted one at a time across tie lines and require a 160 millisecond transmission time for each tone. Unfortunately, when twenty or thirty digits of information transmitted as tones are desired to be sent with a call, the transmission time is too long to efficiently transfer a call between ACDs. Thus, only a few digits of information relating to the overflow call are transmitted across tie lines thereby limiting the routing and application features for the call at the receiving ACD. Therefore, these known ACD networks provide the disadvantage of long call set up and transfer times and further limit the amount of digital information which can be sent with a call.
It is known to transfer a call from one automatic call distributor to another automatic call distributor through the a regular public external telephonic network. The Look-Ahead Interflow feature developed by American Telephone and Telegraph Company establishes a connection via the public external telephonic network from one ACD to a second ACD and transfers a received call at the one ACD to the second ACD. However, the Look-Ahead Interflow feature is limited in the amount and type of data information which is carried with the telephonic call to the second ACD. Look-Ahead Interflow does not provide data to identify which gate the transferred call is to be routed at the receiving ACD. Disadvantageously, the receiving ACD must perform several time consuming processes in attempting to properly route the call. Moreover, since many variable conditions must be met at the receiving ACD to properly route the call, by not having information identifying the gate at which the call is to be routed increases the possibility of a call being routed to a wrong location. Furthermore, the Look-Ahead Interflow does not identify the original sending ACD which transfers the call to the receiving ACD. Thus, there is nothing to prevent the inefficiency of calls being transferred or overflowed from the destination ACD back to the originating ACD which is not able to efficiently route the call.
The Look-Ahead Interflow feature also fails to provide information relating to the number of times a call has been overflowed. Disadvantageously, calls can be continually transferred between numerous ACDs prior to being routed to a gate and serviced by an agent thereby increasing the amount of time to route and service an incoming call to the network.
Furthermore, the Look-Ahead Interflow feature fails to supply the delay time of a call in queue at the originating ACD when transferring the call to another ACD. Consequently, the total delay time for overflow calls cannot be ascertained. In such case, it is not possible to accurately evaluate the overall performance of an automatic call distribution network. For example, a call may have a delay time of fifteen seconds at an originating ACD and an additional five second delay after being overflowed to another or destination ACD. In such known networks, the system administrator at the destination ACD is only aware of the five second delay time and not the twenty second total delay time, and thus calls at the destination ACD are not able to be efficiently routed.
Additionally, the Look-Ahead Interflow feature disadvantageously fails to send Automatic Number Identification (ANI) information with an overflowed call and thus limits the information available for the receiving or destination ACD to effectively route the overflowed call and to trigger various optional features of the system such as announcements, screen displays, etc.
Therefore, these known systems are limited by the limited amount of information transferred with an overflow call, thereby reducing the amount of routing and application features available in such automatic call distribution network with overflow capability.